1. Field of the Invention
The present invention relates generally to wireless communication systems, and more particularly, to the transmission of acknowledgement information in an uplink of a communication system.
2. Description of the Art
A communication system includes a DownLink (DL) that conveys transmission signals from a Base Station (BS or NodeB) to User Equipments (UEs) and an UpLink (UL) that conveys transmission signals from UEs to the NodeB.
More specifically, a UL conveys transmissions of data signals carrying information content, transmissions of control signals providing control information associated with transmissions of data signals in a DL, and transmissions of Reference Signals (RSs), which are commonly referred to as pilot signals. A DL also conveys transmissions of data signals, control signals, and RSs. UL signals may be transmitted over clusters of contiguous REs using a Discrete Fourier Transform Spread Orthogonal Frequency Division Multiplexing (DFT-S-OFDM) method. DL signals may be transmitted using an OFDM method.
UL data signals are conveyed through a Physical Uplink Shared CHannel (PUSCH) and DL data signals are conveyed through a Physical Downlink Shared CHannel (PDSCH).
In the absence of a PUSCH transmission, a UE conveys UL Control Information (UCI) through a Physical Uplink Control CHannel (PUCCH). However, when a UE has a PUSCH transmission, it may convey UCI with data through the PUSCH.
DL control signals may be broadcast or sent in a UE-specific nature. Accordingly, UE-specific control channels can be used, among other purposes, to provide UEs with Scheduling Assignments (SAs) for PDSCH reception (DL SAs) or PUSCH transmission (UL SAs). The SAs are transmitted from the NodeB to respective UEs using DL Control Information (DCI) formats through respective Physical DL Control CHannels (PDCCHs).
The NodeB may configure a UE through higher layer signaling, such as Radio Resource Control (RRC) signaling, a PDSCH, and a PUSCH Transmission Mode (TM). The PDSCH TM or PUSCH TM is respectively associated with a DL SA or a UL SA, and defines whether the respective PDSCH or PUSCH conveys one data Transport Block (TB) or two data TBs.
PDSCH or PUSCH transmissions are either scheduled to a UE by a NodeB through higher layer signaling or through physical layer signaling (e.g., a PDCCH) using a respective DL SA or UL SA, or correspond to non-adaptive retransmissions for a given Hybrid Automatic Repeat reQuest (HARQ) process. Scheduling by higher layer signaling is referred to as Semi-Persistent Scheduling (SPS), and scheduling by a PDCCH is referred to as dynamic. A PDCCH may also be used to release an SPS PDSCH. If a UE fails to detect a PDCCH, this event is referred to as Discontinuous Transmission (DTX).
The UCI includes ACKnowledgment (ACK) information associated with a HARQ process (HARQ-ACK). The HARQ-ACK information may include multiple bits indicating the correct or incorrect detection of multiple data TBs. Typically, a correct detection of a data TB is indicated by a positive acknowledgment (i.e., an ACK) while an incorrect detection is indicated by a Negative ACK (NACK). If a UE misses (e.g., fails to detect) a PDCCH, it may explicitly or implicitly (absence of a signal transmission) indicate DTX (tri-state HARQ-ACK information) or both a DTX and an incorrect reception of a TB can be represented by a NACK (in a combined NACK/DTX state).
In Time Division Duplex (TDD) systems, DL and UL transmissions occur in different Transmission Time Intervals (TTIs), which are referred to as subframes. For example, in a frame including 10 subframes, some the subframes may be used for DL transmissions and some may be used for UL transmissions.
If a PDSCH conveys one data TB, respective HARQ-ACK information typically consists of one bit that is encoded as a binary 1′, if the TB is correctly received (i.e., an ACK value), and as a binary ‘0’, if the TB is incorrectly received (i.e., a NACK value). If a PDSCH conveys two data TBs, in accordance with a Single-User Multiple Input Multiple Output (SU-MIMO) transmission method, respective HARQ-ACK information typically consists of two bits [o0ACKo1ACK] with o0ACK for a first TB and o1ACK for a second TB.
FIG. 1 illustrates a conventional TTI for a PUSCH or a PUCCH.
Referring to FIG. 1, a TTI consists of one subframe including two slots for PUSCH 110A or PUCCH 110B transmission. Each slot 120A and 120B includes NsymbUL symbols 130A used for signaling data or HARQ-ACK information in a PUSCH, or NsymbUL symbols 130B used for HARQ-ACK information in a PUCCH, and Reference Signals (RS) 140A or 140B, which are used for channel estimation and coherent demodulation of received data or HARQ-ACK information. The transmission BandWidth (BW) consists of frequency resource units that are referred to as Physical Resource Blocks (PRBs). Each PRB consists of NscRB sub-carriers, or Resource Elements (REs). For PUSCH transmission, a UE is allocated MPUSCH PRBs for a total of MscPUSCH=MPUSCH·NscRB REs 150A. For PUCCH transmission, a UE is allocated 1 PRB 150B, which may be in two different BW locations in each of the two subframe slots.
FIG. 2 illustrates a conventional HARQ-ACK transmission structure in a PUCCH subframe slot.
Referring to FIG. 2, HARQ-ACK bits b 210 modulate 220 a Constant Amplitude Zero Auto-Correlation (CAZAC) sequence 230, for example, using Binary Phase Shift Keying (BPSK) with b=b0 or Quaternary Phase Shift Keying (QPSK) with b=(b0,b1). The modulated CAZAC sequence is then transmitted after performing an Inverse Fast Frequency Transform (IFFT) 240. The RS is transmitted through a non-modulated CAZAC sequence after performing an IFFT 250.
FIG. 3 is a block diagram illustrating of a conventional transmitter for a PUCCH.
Referring to FIG. 3, a CAZAC sequence 310 can be used without modulation for an RS or with modulation for HARQ-ACK information. The transmitter in the FIG. 3 includes a selector 320, a sub-carrier mapper 330, an IFFT unit 340, a Cyclic Shifter 350, a Cyclic Prefix (CP) inserter 360, and a filter 370 for time windowing. For sub-carrier mapping in the sub-carrier mapper 330, the selector 320 selects a first PRB and a second PRB for transmission of the CAZAC sequence in a first slot and a second slot, respectively. Subsequently, the IFFT unit 340 performs IFFT, and the Cyclic Shifter 350 applies a Cyclic Shift (CS) to the output of the IFFT unit 340. A CP and filtering are applied by the CP inserter 360 and the filter 370. Thereafter, the signal 380 is transmitted. Additional transmitter circuitry such as a Digital-to-Analog Converter (DAC), analog filters, amplifiers, transmitter antennas, etc., are not shown for brevity.
FIG. 4 is a block diagram illustrating a conventional receiver diagram for a PUCCH.
Referring to FIG. 4, the receiver includes a filter 420 for time windowing, a CP remover 430, a CS restorer 440, a Fast Fourier Transform (FFT) unit 450, a sub-carrier de-mapper 460, a selector 465, and a multiplier 470. An antenna (not shown) receives an analog signal and after further processing units (such as filters, amplifiers, frequency down-converters, and Analog-to-Digital Converters (ADCs) that are not shown for brevity), a digital received signal 410 passes through the filter 420 and the CP remover 430. Subsequently, a CS is restored by the CS restorer 440, the FFT 450 unit applies FFT, for sub-carrier demapping in the sub-carrier demapper 460, a selector 465 selects REs in a first PRB and a second PRB in a first slot and in a second slot, respectively, and a multiplier correlates 470 the REs with a replica of a CAZAC sequence 480. The output 490 may then be passed to a channel estimation unit, such as a time-frequency interpolator, when a subframe symbol conveys a RS, or to a detection unit, when a subframe symbol conveys a HARQ-ACK signal.
Different CSs of a same CAZAC sequence provide orthogonal CAZAC sequences and can be allocated to different UEs to achieve orthogonal multiplexing of HARQ-ACK signal transmissions in the same PRB. If Ts is a symbol duration, the number of such CSs is approximately └Ts/D┘, where D is a channel propagation delay spread and └ ┘ is a floor function that rounds a number to its immediately lower integer.
In addition to orthogonal multiplexing of HARQ-ACK signals and an RS in a same PRB using different CS of a CAZAC sequence, orthogonal multiplexing may also be in the time domain using Orthogonal Covering Codes (OCC). For example, in FIG. 2, a HARQ-ACK signal can be modulated by a length-4 OCC, such as a Walsh-Hadamard (WH) OCC, while an RS can be modulated by a length-3 OCC, such as a DFT OCC (not shown). When using an OCC, the multiplexing capacity per PRB increases by a factor of 3 (determined by the OCC with the smaller length). The sets of WH OCCs {W0, W1, W2, W3}, and DFT OCCs {D0, D1, D2}, are respectively
      [                                        W            0                                                            W            1                                                            W            2                                                            W            3                                ]    =                    [                                            1                                      1                                      1                                      1                                                          1                                                      -                1                                                    1                                                      -                1                                                                        1                                      1                                                      -                1                                                                    -                1                                                                        1                                                      -                1                                                                    -                1                                                    1                                      ]            ⁢                          ⁢              and        ⁢                                  [                                                            D                0                                                                                        D                1                                                                                        D                2                                                    ]              =                  [                                            1                                      1                                      1                                                          1                                                      e                                                      -                    j                                    ⁢                                                                          ⁢                  2                  ⁢                                      π                    /                    3                                                                                                      e                                                      -                    j                                    ⁢                                                                          ⁢                  4                  ⁢                                      π                    /                    3                                                                                                          1                                                      e                                                      -                    j                                    ⁢                                                                          ⁢                  4                  ⁢                                      π                    /                    3                                                                                                      e                                                      -                    j                                    ⁢                                                                          ⁢                  2                  ⁢                                      π                    /                    3                                                                                      ]            .      
Table 1 presents a mapping for a PUCCH resource nPUCCH used for a HARQ-ACK signal and an RS transmission to an OCC noc and a CS α, assuming 6 CS per symbol and a length-3 OCC (with 3 CS used for each OCC). If all resources within a PUCCH PRB are used, resources in an immediately next PRB can be used.
TABLE 1PUCCH Resource Mapping to OCC and CS.OCC noc for a HARQ-ACK and foran RSCS αW0, D0W1, D1W3, D20nPUCCH = 0nPUCCH = 61nPUCCH = 32nPUCCH = 1nPUCCH = 73nPUCCH = 44nPUCCH = 2nPUCCH = 85nPUCCH = 5
A PDCCH is transmitted in elementary units that are referred to as Control Channel Elements (CCEs). Each CCE may consist of 36 REs. UEs are informed of a total number of CCEs, NCCE through a transmission of a Physical Control Format Indicator CHannel (PCFICH) by a serving NodeB. The PCFICH indicates a number of OFDM symbols used for PDCCH transmissions in a respective DL subframe. A one-to-one mapping can exist between PUCCH resources (PRB, CS, OCC) for HARQ-ACK signal transmission and PDCCH CCEs. For example, if a single PUCCH resource is used for HARQ-ACK signal transmission, it may be derived from the CCE with the lowest index in a PDCCH conveying a respective DL SA.
In TDD systems, DL and UL transmissions occur in different subframes and M≥1 DL subframes may be associated with a single UL subframe. The association is in the sense that HARQ-ACK information generated in response to reception of data TBs in M≥1 DL subframes is transmitted in a single UL subframe. This set of M≥1 DL subframes is commonly referred to as a bundling window. Denoting a DL subframe index by m=0, 1, . . . , M−1, a number of CCEs for a PCFICH value of p (N0=0) by Np, and a first PDCCH CCE of a DL SA in subframe m by nCCE(m), a PUCCH resource indexing for HARQ-ACK signal transmission can be as described below.
A UE first selects a value p∈{0, 1, 2, 3} providing Np≤nCCE(m)<Np+1 and then considers nPUCCH,m=(M−m−1)×Np+m×Np+1+nCCE(m)+NPUCCH as a PUCCH resource available for HARQ-ACK signal transmission in response to a DL SA in DL subframe m, where Np=max{0,└[NRBDL×(NscRB×p−4)]/36┘}, NPUCCH is an offset informed to a UE by higher layer signaling, NscRB is a number of sub-carriers and NRBDL is a number of PRBs in the DL operating BW.
HARQ-ACK information in a PUCCH may be conveyed with several methods including HARQ-ACK time-domain bundling and HARQ-ACK multiplexing using channel selection (referring to a selection of a PUCCH resource from a set of available PUCCH resources). In both cases, HARQ-ACK spatial-domain bundling applies where a UE generates an ACK, only if it receives all data TBs in a PDSCH correctly, and generates a NACK otherwise.
With HARQ-ACK time-domain bundling, a UE generates an ACK, only if it receives all TBs in a bundling window correctly, and generates a NACK otherwise. Therefore, HARQ-ACK time-domain bundling results in unnecessary retransmissions as a NACK is sent even when the UE correctly receives some of the TBs in a bundling window.
With HARQ-ACK multiplexing using channel selection, a UE conveys HARQ-ACK information for each DL subframe in a bundling window by selecting a PUCCH resource from a set of possible resources and by modulating the HARQ-ACK signal using QPSK modulation.
Table 2 describes HARQ-ACK multiplexing using channel selection for M=3 in a TDD system with a single DL cell and a single UL cell. Specifically, a UE modulates a HARQ-ACK signal using the QPSK constellation point and selects one of PUCCH resources nPUCCH(0), nPUCCH(1), or nPUCCH(2), which are respectively determined by a first CCE of a respective PDCCH conveying a DL SA in a respective first, second, or third DL subframe (if any).
Explicit DTX indication is possible by including a Downlink Assignment Index (DAI) Information Element (IE), which indicates an accumulative number of PDSCH transmission(s) to a UE (the DAIIE is a counter within a bundling window), in DCI formats conveying DL SAs.
TABLE 2HARQ-ACK Multiplexing with Channel Selection for M = 3 DL SubframesEntryHARQ-ACK(0), HARQ-ACK(1), NumberHARQ-ACK(2)nPUCCHConstellation1ACK, ACK, ACKnPUCCH,21, 12ACK, ACK, NACK/DTXnPUCCH,11, 13ACK, NACK/DTX, ACKnPUCCH,01, 14ACK, NACK/DTX, NACK/DTXnPUCCH,00, 15NACK/DTX, ACK, ACKnPUCCH,21, 06NACK/DTX, ACK, NACK/DTXnPUCCH,10, 07NACK/DTX, NACK/DTX, ACKnPUCCH,20, 08DTX, DTX, NACKnPUCCH,20, 19DTX, NACK, NACK/DTXnPUCCH,11, 010NACK, NACK/DTX, NACK/DTXnPUCCH,01, 011DTX, DTX, DTXN/AN/A
When HARQ-ACK information is transmitted in a PUSCH, it is encoded depending on a number of HARQ-ACK bits being conveyed. Assuming HARQ-ACK spatial-domain bundling, each HARQ-ACK bit conveys an outcome of each PDSCH reception and is encoded as a binary ‘1’, if the respective TB(s) are correctly received (i.e., an ACK), and is encoded as a binary ‘0’, if the respective TB(s) are incorrectly received (i.e., a NACK). Therefore, an individual HARQ-ACK bit is conveyed for each PDSCH reception. When HARQ-ACK information consists of O=1 bit o0ACK, it is encoded using repetition coding. When HARQ-ACK information consists of O=2 bits [o0ACK o1ACK], it is encoded using a (3, 2) simplex code, as described in Table 3 for Qm data modulation bits, where o2ACK(o0ACK+o1ACK)mod 2.
TABLE 3Encoding for 1 and 2 HARQ-ACK Information Bits.Encoded HARQ-Encoded HARQ-QmACK-1 bitACK-2 bits2[o0ACK y][o0ACK o1ACK o2ACK o0ACK o1ACK o2ACK]4[o0ACK y x x][o0ACK o1ACK x x o2ACK o0ACK x x o1ACK o2ACK x x]6[o0ACK y x x x x][o0ACK o1ACK x x x x o2ACK o0ACK x x x x o1ACK o2ACK x x x x]
When HARQ-ACK information corresponds to a possible reception of more than 2 PDSCHs (assuming HARQ-ACK spatial-domain bundling) and consists of respective 3≤OACK≤11 bits, the coding may be by a (32, OACK) Reed-Mueller (RM) block code. Denoting the HARQ-ACK information bits by o0ACK o1ACK, . . . , oOACK−1ACK and the encoded HARQ-ACK bits by {tilde over (q)}0ACK {tilde over (q)}1ACK, . . . , {tilde over (q)}31ACK,
                    q        ~            i      ACK        =                  ∑                  n          =          0                          O          -          1                    ⁢                        (                                    o              n              ACK                        ·                          M                              i                ,                n                                              )                ⁢        mod        ⁢                                  ⁢        2              ,where Mi,n are basis sequences of an RM code and i=0, 1, . . . , 31. The output bit sequence q0ACK, q1ACK, q2ACK, . . . , qQACK−1ACK is obtained by a circular repetition of the bit sequence {tilde over (q)}0ACK{tilde over (q)}1ACK, . . . , {tilde over (q)}31ACK, such that the bit sequence length is equal to QACK, which is the total number of coded HARQ-ACK symbols in a PUSCH.
FIG. 5 is a block diagram illustrating a conventional transmitter for data and HARQ-ACK in a PUSCH.
Referring to FIG. 5, the transmitter includes a data encoder 515, an RM encoder 520, a puncturer/inserter 530, a DFT unit 540, a sub-carrier mapper 550, a selector 555, an IFFT unit 560, a CP inserter 570, and a filter 580 for time windowing. Data information bits 505 and HARQ-ACK information bits 510 are respectively provided to the data encoder 515 and the RM encoder 520. For two HARQ-ACK information bits, a simplex encoder is used instead of the RM encoder 520. Encoded data bits are subsequently punctured and replaced by encoded HARQ-ACK bits by the puncturer/inserter 530. The result is then input to a DFT unit 540. A selector 555 selects REs corresponding to the PUSCH transmission BW for subcarrier mapping in the sub-carrier mapper 550, which are then input to the IFFT unit 560. A CP is inserted by the CP inserter 570, and the CP inserted signal then passes through the filter 580 before being transmitted 590. Again, additional transmitter circuitry is not illustrated for conciseness. Also, the modulation process for the transmitted bits is omitted for brevity.
FIG. 6 is a conventional block diagram illustrating a receiver block for data and HARQ-ACK in a PUSCH.
Referring to FIG. 6, the receiver includes a filter 620 for time windowing, a CP remover 630, an FFT unit 640, a sub-carrier de-mapper 650, a selector 655, an Inverse DFT (IDFT) unit 660, a de-multiplexer 670, a data decoder 680, and an RM decoder 685. After an antenna (not shown) receives a Radio-Frequency (RF) analog signal and further processing units (not shown) convert the analog signal to a digital signal 610, the digital signal 610 passes through the filter 620 and the CP removal unit 630. The output of the CP removal unit 630 is provided to the FFT unit 640, and a selector 655 controls the sub-carrier de-mapper 650 to select the REs used by the transmitter. The obtained values are provided to the IDFT unit 660 and the de-multiplexer 670, which outputs coded data bits. that the coded data bits are then provided to the data decoder 680 and the coded HARQ-ACK bits are then provided to the RM decoder 685 to respectively output data information bits 690 and HARQ-ACK information bits 695. For two HARQ-ACK information bits, a simplex decoder is used instead of the RM decoder 685. Similar to the transmitter illustrated in FIG. 5, receiver functionalities such as channel estimation, demodulation, and decoding are not illustrated in FIG. 6 for brevity.
In order to increase the supportable data rates to a UE, a NodeB can configure multiple cells to a UE in both a DL and a UL to effectively provide higher operating BWs. For example, to support communication over 40 MHz, two 20 MHz cells can be configured to a UE. A UE is always configured a DL cell and a UL cell to maintain communication and each such cell is referred to as Primary cell (Pcell). Additional cells a UE may be configured are referred to as Secondary cells (Scells).
A transmission of HARQ-ACK information can be in a PUCCH of the UL Pcell. For HARQ-ACK multiplexing using channel selection, a separate PUCCH resource is assigned in a UL Pcell for HARQ-ACK signal transmission in response to a PDSCH reception in each subframe of a bundling window and each DL cell.
For two configured cells and a bundling window size of M>1 DL subframes, denoting PUCCH resources associated with reception of PDSCH(s) on the DL Pcell by nPUCCH,0 and nPUCCH,1 and PUCCH resources associated with reception of PDSCH(s) on the Scell and by HARQ-ACK(j), 0≤j≤M−1, by nPUCCH,2 and nPUCCH,3, the ACK/NACK/DTX response for a PDSCH with corresponding DAI value in a PDCCH equal to ‘j+1’, a UE performs channel selection according to Table 4 for M=3 and Table 5 for M=4 and transmits a HARQ-ACK signal using QPSK modulation {b(0),b(1)} on PUCCH resource nPUCCH. For the last state in Table 4 and the last two states in Table 5, there is no transmission in a PUCCH, as a UE cannot determine a valid PUCCH resource. The value ‘any’ can be either ‘ACK’ or ‘NACK/DTX’.
TABLE 4HARQ-ACK Multiplexing with Channel Selection for M = 3 DL Subframes and 2 Configured Cells.Primary CellSecondary CellResourceConstellationHARQ-ACK(0),HARQ-ACK(0), HARQ-nPUCCHb(0), b(1)HARQ-ACK(1),ACK(1), HARQ-HARQ-ACK(2)ACK(2)ACK, ACK, ACKACK, ACK, ACKnPUCCH,11, 1ACK, ACK,ACK, ACK, ACKnPUCCH,10, 0NACK/DTXACK, NACK/DTX, anyACK, ACK, ACKnPUCCH,31, 1NACK/DTX, any, anyACK, ACK, ACKnPUCCH,30, 1ACK, ACK, ACKACK, ACK,nPUCCH,01, 0NACK/DTXACK, ACK,ACK, ACK,nPUCCH,31, 0NACK/DTXNACK/DTXACK, NACK/DTX, anyACK, ACK,nPUCCH,00, 1NACK/DTXNACK/DTX, any, anyACK, ACK,nPUCCH,30, 0NACK/DTXACK, ACK, ACKACK, NACK/DTX, anynPUCCH,21, 1ACK, ACK,ACK, NACK/DTX, anynPUCCH,20, 1NACK/DTXACK, NACK/DTX, anyACK, NACK/DTX, anynPUCCH,21, 0NACK/DTX, any, anyACK, NACK/DTX, anynPUCCH,20, 0ACK, ACK, ACKNACK/DTX, any, anynPUCCH,11, 0ACK, ACK,NACK/DTX, any, anynPUCCH,10, 1NACK/DTXACK, NACK/DTX, anyNACK/DTX, any, anynPUCCH,01, 1NACK, any, anyNACK/DTX, any, anynPUCCH,00, 0DTX, any, anyNACK/DTX, any, anyNo Transmission
TABLE 5HARQ-ACK Multiplexing with Channel Selection for M = 4 DL Subframesand 2 Configured Cells.Primary CellSecondary CellResourceConstellationHARQ-ACK(0), HARQ-HARQ-ACK(0), HARQ-nPUCCHb(0), b(1)ACK(1), HARQ-ACK(2),ACK(1), HARQ-ACK(2),HARQ-ACK(3)HARQ-ACK(3)ACK, ACK, ACK,ACK, ACK, ACK,nPUCCH,11, 1NACK/DTXNACK/DTXACK, ACK, NACK/DTX,ACK, ACK, ACK,nPUCCH,10, 0anyNACK/DTXACK, DTX, DTX, DTXACK, ACK, ACK,nPUCCH,31, 1NACK/DTXACK, ACK, ACK, ACKACK, ACK, ACK,nPUCCH, 31, 1NACK/DTXNACK/DTX, any, any, anyACK, ACK, ACK,nPUCCH,30, 1NACK/DTX{ACK, NACK/DTX, any,ACK, ACK, ACK,nPUCCH,30, 1any}, except for {ACK, DTX,NACK/DTXDTX, DTX}ACK, ACK, ACK,ACK, ACK, NACK/DTX,nPUCCH,01, 0NACK/DTXanyACK, ACK, NACK/DTX,ACK, ACK, NACK/DTX,nPUCCH,31, 0anyanyACK, DTX, DTX, DTXACK, ACK, NACK/DTX,nPUCCH,00, 1anyACK, ACK, ACK, ACKACK, ACK, NACK/DTX,nPUCCH,00, 1anyNACK/DTX, any, any, anyACK, ACK, NACK/DTX,nPUCCH,30, 0any{ACK, NACK/DTX, any,ACK, ACK, NACK/DTX,nPUCCH,30, 0any}, except for {ACK, DTX,anyDTX, DTX}ACK, ACK, ACK,ACK, DTX, DTX, DTXnPUCCH,21, 1NACK/DTXACK, ACK, ACK,ACK, ACK, ACK, ACKnPUCCH,21, 1NACK/DTXACK, ACK, NACK/DTX,ACK, DTX, DTX, DTXnPUCCH,20, 1anyACK, ACK, NACK/DTX,ACK, ACK, ACK, ACKnPUCCH,20, 1anyACK, DTX, DTX, DTXACK, DTX, DTX, DTXnPUCCH,21, 0ACK, DTX, DTX, DTXACK, ACK, ACK, ACKnPUCCH,21, 0ACK, ACK, ACK, ACKACK, DTX, DTX, DTXnPUCCH,21, 0ACK, ACK, ACK, ACKACK, ACK, ACK, ACKnPUCCH,21, 0NACK/DTX, any, any, anyACK, DTX, DTX, DTXnPUCCH,20, 0NACK/DTX, any, any, anyACK, ACK, ACK, ACKnPUCCH,20, 0{ACK, NACK/DTX, any,ACK, DTX, DTX, DTXnPUCCH,20, 0any}, except for {ACK, DTX,DTX, DTX}{ACK, NACK/DTX, any,ACK, ACK, ACK, ACK0, 0any}, except for {ACK, DTX,DTX, DTX}ACK, ACK, ACK,NACK/DTX, any, any, anynPUCCH,11, 0NACK/DTXACK, ACK, ACK,{ACK, NACK/DTX, any,nPUCCH,11, 0NACK/DTXany}, except for {ACK,DTX, DTX, DTX}ACK, ACK, NACK/DTX,NACK/DTX, any, any, any nPUCCH,10, 1anyACK, ACK, NACK/DTX,{ACK, NACK/DTX, any,nPUCCH,10, 1anyany}, except for {ACK,DTX, DTX, DTX}ACK, DTX, DTX, DTXNACK/DTX, any, any, any nPUCCH,01, 1ACK, DTX, DTX, DTX{ACK, NACK/DTX, any,nPUCCH,0any}, except for {ACK, 1, 1DTX, DTX, DTX}ACK, ACK, ACK, ACKNACK/DTX, any, any, any nPUCCH,01, 1ACK, ACK, ACK, ACK{ACK, NACK/DTX, any,nPUCCH,01, 1any}, except for {ACK, DTX, DTX, DTX}NACK, any, any, anyNACK/DTX, any, any, anynPUCCH,00, 0NACK, any, any, any{ACK, NACK/DTX, any,nPUCCH,00, 0any}, except for {ACK,DTX, DTX, DTX}{ACK, NACK/DTX, any,NACK/DTX, any, any, any nPUCCH,00, 0any}, except for {ACK, DTX,DTX, DTX}{ACK, NACK/DTX, any,{ACK, NACK/DTX, any,nPUCCH,00, 0any}, except for {ACK, DTX,any}, except for {ACK,DTX, DTX}DTX, DTX, DTX}DTX, any, any, anyNACK/DTX, any, any, anyNo TransmissionDTX, any, any, any{ACK, NACK/DTX, any,No Transmissionany}, except for {ACK,DTX, DTX, DTX}
For a single-cell operation, HARQ-ACK multiplexing with channel selection conveys a number of HARQ-ACK states in a PUCCH, as described in the example of Table 3 for M=3, while HARQ-ACK transmission in a PUSCH conveys an individual information bit for each DL subframe in a bundling window (or for a number of DL subframes specified by a DAI IE in a UL SA scheduling a PUSCH transmission, if any). Therefore, a maximum of M HARQ-ACK information bits are conveyed. However, if a same approach for HARQ-ACK transmission in a PUSCH were to be followed for multi-cell (DL CA: Down Link Carrier Aggregation) operation, the maximum number of HARQ-ACK information bits would linearly scale with the number of configured cells to a UE. However, increasing the number of HARQ-ACK information bits in a PUSCH for UEs configured HARQ-ACK multiplexing with channel selection in a PUCCH may result in a failure to provide the required HARQ-ACK reception reliability and will often lead to different operations depending on the channel, PUCCH, or PUSCH, used to transmit the HARQ-ACK information.